Battery operated electric motor control for vehicle



June 8, 1965 D. E. coLvlLL. l-:TAL

BATTERY OPERATED ELECTRIC MOTOR CONTR-OL FOR VEHICLE Filed Dec'. 29, 1960 E N N N MM5@ H W@ @G A v, 0 N .I SNWMMM blLn I M? 5 Q) Alw@ VJ wm NQ QQ NQ En o on HMT on. I, \.l NM ANAH h\ I1 N H N H O Q \R\ @mfr/ NGN @no D K RR W m 1| $N\ N.W\ NN Q* H NK\ Nm EVN A @S u Q E ww \l N\ 1 mm, wm Nm uvm. wm www mw QN v@ QQ QQ @Q R mi l WMI wm l 1 L, E 4

um, v NQ @v N w v x. NTQ w IJ W N WQ Q I I l WQJMM I l Il V v V @Qi V QQLV vmklv J NWT/Nw QQ QQ QQ u United States Patent @thee 3,188,543 Patented June 8, 15565 3,18%,543 BATTERY OFERATED ELECTREC MTR CUNTRL FR VEHECLE Donald E. Colviil, Richard L. Sprague, Kenneth-H. Ciayton, Richard L. Konopa, and Robert E. .lohnsoin all of Anderson, Ind., assignorsvto General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 29, 1960, Ser. No. 79,355

4 Claims. (Cl. 313-139) This invention relates to control systems for controlling the speed of an electric motor that drives a vehicle.

One of theobjects of this invention is to provide a control system for an electric motor-driven vehicle wherein the motor is fed from batteries and wherein switching means are provided for connecting they batteries in series or in parallel with thernotor and for connecting the batteries with the motor through a resistor and further whereinmeans have provided for insuring that the voltage applied tor themotor as determined by the connections of the batteries and resistor is increased in steps when increasing the speed of the motor to thereby minimize sudden high current drains on thebatteriesand also to thereby provide a smooth acceleration.

Another object of this invention is to provide a motor control system wherein the motor is fed from batteries and wherein switching means are provided for connecting the batteries in series or in parallel with the motor and with a resistor to vary the voltage applied to the motor, and further wherein centrifugal switch means is provided that is driven by the motor and which operates to insure that the voltage applied to the motor will be increased only in step-wise fashion when it is desired to accelerate theV motor.

A further object of this invention is to provide a control system for the motor of an electric motor-driven vehicle that is operative to provide forward and reverse movement of the vehicle and wherein means are provided for preventing suddenly shifting from a forward to a reverse movement and vice versa when the vehicle is in motion.

Further objects and advantages 'of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein the preferred embodiment of the present invention is clearly shown. y

In the drawings:

vThe single ligure drawing is a schematic electrical circuit diagram of a motor contr-olsystem made in accordance with this invention.

Referring now to the drawing, theV reference numeral -generally designates a series type D.C. motor which has an armature 12tand a iield winding 14. The armature 12 is mechanically connected with the wheels 15 and 16 of the vehicle that is to be driven by the motor 12. One side of the motor armature 12 is connected directly to ground as is apparent from the drawing, while the opposite side of the armature 12 is connected witha lead wire 18. The field winding 14 of the motor is connected with the junction and with theV lead wire 22.

The direction of rotation of theA motor` 1 is controlled by a pair of electromagnetic switches. One of these switches comprises the c oil winding 24 and the contactors 24a andj24b which are shifted when the coil winding 24 is energized. When the coil winding 24 isvnotjenergized, the contactor 24a shorts the, contacts 26 and 28 while the contactor Zlib is maintained outof engagement with contacts 30 and 32. When coil winding 24 is energized, the contactor 24a shifts out of engagement with contacts 26v and28 and the contactor 24b shorts the xed contacts 30 and 32.

The other electromagnetic switch includes the coil winding 34 which controls the shifting of contactors 34a and 34b. It can be seen that when the coil winding 34 is deenergized, thelco'ntactor 34a 'connects contacts 36 and 3S; and when the coil winding 34 is energized, the contactor 3411 connects-the fixed contacts 40 and 42.

The contacts38 and V42 are connected with lead wire 22 whereas the contacts 2 6'and 36 are connected with lead wire 1S.l The'contacts 28 and v30 are connected with junction. 2t)n and are therefore connected to one side of the field winding14. The Xed contacts 32 and 40 are conneted With'a lead wireifi,4

The lead wire 44 isrconnected to one side of a power resistor 46 which is adapted to control the amount of voltageapplied to the meterlo. The powerrresistor 46 is at times shortvcircuited by a contactor 48a which is a normally'op'en: contact but which is closed whenever the relay coil`48is energized. The resistor 46 andthe contactor 48a arejconnected .with a lead wire 5i) and it is seen that this lead wireySil` is connected to one side of a relay operated contactor 52a. The contactor 52a is a normally open contact but will bevpnlled to` a position to connect lead wires Stiand 54. whenever the coil windingy 52 Vis energized. It is pointed out that the arrow through the contactor 4&1 indicates that this is anormally open contactor but will be pulled to a c losedposition whenever the relay coil 48 is energized.

The lead wire 54 is connected with a lead wire 56, and it is seen that this lead wire is vconnected with the junction 58. The junction 58 is connected .to one side of a battery 60 which may be, for example, a l2 volt battery. The opposite sideof the battery 60 is connected with junction 62, and it is seen that this junction is connected with junction `fiand the lead wire 65. The power supply systern forthe'motorincludes another battery 68 which also maybe a l2 volt battery. It is seen that one side of the battery 68 is connected directlyto ground whereas an opposite side of this battery is connected with the lead wire 70.

The batteries 60 and 68 can be connected in series or in parallel with` the motor 10 by a magnetic switch which is generally designated byl reference numeral '72. This magnetic switchinclndesthecoil winding 74which operates a plunger '76.r The plunger 76 carries the contactors 7S, 80, `and` 82. When the coilwinding 74 is not energized, the contactor 7Sqis out ofvengagement with fixed contactsjirand ti(Y and the contactor Si) is out of engagement with xedgcontacts 88 and 95). The contactor S2 connects fixed contacts 92 and 94 when the coil winding is deenergizedt When'coil windingf74is energized, it can be seen that contactor 82 willbe shifted ont of yengagement with ixed contacts 92kand 94 and that contaotors '78 and) will connect respectively fixed contacts S4 and 85 and fixed contacts S8 and Sth itis seen that the iixed contact S4 is connected to ground via lead Awire 9,5. The contacto is connected with junction 64. The` contact 96 is connected withjjunction 58. whereas the contact ed is connected with lead wir-e771) and is therefore connected to one side of the Abattery 68, The contact 92 is connected to one side of battery 68 andthe contact 94,*is connected with Vthe junction 6,4.i

It is pointed ont that when the coil winding 74.is not energized, the batteries are connected in Series between groundpand .the junction 58: so ,that 24 volts is applied between junction 58 and ground. O'n the other hand, when the coil winding 74 is energized, the batteries 60 and 68 are'conne'cted in parallel so that there is only`12 voltsap- 4pearin'gi between junction 5S and ground.

The lead wire 7twhich is connected with the positive terminal of battery V68 is connected to one side of a manually operable key switch designated by reference numeral i tactor 116 of a manually operable switch generally designated by reference numeral 112. This switch 112 has fixed contacts 114 and 116. As will become more readily apparent hereafter, when the contactor 110 is shifted into engagement with fixed contact 116, the motor 16 is operated to provide for reverse movement of the vehicle. On the other hand, when the contactor 110 is shifted into engagement with the fixed contact 114, the vehicle -will move in a forward direction. When contactor 110 is out of engagement with fixed contacts 114 and 116, the vehicle will be at rest and will not move in either direction.

The fixed contact 116 is connected with a lead wire 118, and this lead wire connects with the lead wire 120. The lead wire 126 is connected between a diode 122 and the relay coil winding 24. The opposite side of relay coil winding 24 is connected with the lead wire 124.

The fixed contact 114 is connected with the lead wire 126. The lead wire 126 is connected to one side of relay coil winding 34 and to one side of a relay coil winding 126. The coil winding 128 controls the contactor 12651 which is a normally open contact. When coil winding 128 is energized, the contactor 128a is pulled to a closed position. lt is seen that the relay coil winding 12S is connected directly across lead wires 124 and 126. The coil winding 34 is likewise connected directly across the lead wires 124 and 126. j

Lead wire 126 connects to one side of diode 130. The oposite side of diode 136 is connected to diode 134 by lead wires 136 and 132. A relay coil winding 136 is connected 52. The lead wire 162 is connected to one side of a centrifugal switch that includes the shiftable contactor 166. This centrifugal switch is driven by the motor 11i and will connect the lead wires 162 and 168 whenever the motor attains some predetermined speed. The speed at which the contactor 166 shifts to a closed position may be roughly the same as the speed that the contactor 146 shifts to an open position.

The accelerator-operated switch 152 is connected between lead wire 176 and the junction 172. The junction 172 is connected to one side of a centrifugal switch that includes the centrifugally operated contactor 174. The

, opposite side of this switch is conected with lead wire 176.

The centrifugal switch that includes the contactor 174 is driven by the motor 10 or by the drive system for the wheels 15 and 16 and will be shifted to a closed position at a speed higher than that required to shift the contactor 166 to a closed position. y

The junction 172 is connected to still another centrifugal switch including the centrifugally operated contactor 178. The opposite side of this centrifugal switch is connected with the junction 186. The centrifugal switch that includes the contactor 178 is driven by the motor 10 or the system that it drives and will be shifted to a closed position at a speed that is still higher than the speed required to causeV a closure of the switch that includes contactor 174. It thus is seen that as the motor 10 is accelerated, the contactor 166 will be first shifted to a closed position, then the contactor 174 and then the contactor 178.

The junction 186 is connected to one side of the accelerator-operated switch 154 and is also connected to one side of a diode 132 and to one side of a relay coil winding 184. The relay coil 184 controls the shifting of a shiftable contact 184a which cooperates with a fixed contact 166. When the relay coil 184 is energized,

' the Contact 184a is shifted into engagement with the fixed between lead wires 138 and 124. The coil winding 136 controls the operation of contactor 136a which is a normally open contact but which is shifted to a closed posiwhenever the relay coil 136 is energized. A diode 140 is connected between lead wire 124 and lead wire 142. The lead wire 142 connects to one side of relay coil winding 74. The diode 134 is connected between lead wire 132 and the lead wire 144. A centrifugal switch including contactor 146 is connected between junction 104 and the lead wire 144. This contactor 146 normally connects the junction 164 and the lead wire 144, but will be shifted to an open position when the speed of the motor 10 reaches some predetermined value. The centrifugal switch is mechanically coupled to the motor or to the motorV drive system for the wheels in order to operate as described.

The control system of this invention includes switches 148, 150, 152, and 154, all of which are operated by an accelerator pedal 156. The switches are so connected-with the accelerator pedal 156 that initial depression of the accelerator pedal will close the switch 148. A further depression of the accelerator pedal will then close switch 156 and still further depressionwill close the switch 152. When the accelerator pedal has been shifted a sufficient distance to close the switch 152, the switches 14S and 150 are maintained closed. If the accelerator pedal is still further depressed, the switch 154 will be closed. The switch 154, as will become more readily apparent hereinafter, is an override switch and the accelerator pedal 156 may therefore be connected with some detent or spring contact 186. between junction 180 and the Vjunction 168. A diode 191i is connected between junction 188 and the lead wire 166.

The junction 188 is connected with lead wire 194 which is in turn connected to one side of relay coil windings means which provides a feel before the switch 154 can 196 and 198. The opposite side of relay coil winding 196 is connected with lead wire 66. The relay coil winding 196 controls the shiftahle movement of a contactor 196er which cooperates with xed contacts 2110 and 202. When relay coil 196 is not energized, the contact 196:1 engages the fixed contact 260. When relay coil 196 is energized, the contact 19661 leaves the contact 266 and shifts into engagement with fixed contact 262. It is seen that the relay coil 198 is connected between fixed contact 202 and the lead wire 194. The relay coil 198i operates ,the normally closed contactor 191m which is connected between the relay coil winding 74 and the junction 194. When the relay coil winding 193 is energized, the contactor 19M will be shifted to an open position. 1

In the operation of the system that has just been described, if assumed that the driver of the electrically driven vehicle desires to move in a forward direction, the contactor 116 of switch 112 is shifted into engagement with the fixed contact 114. Upon closing of the keyV a circuit between lead wire 44 and one side of the field winding 14. The circuit will be complete to the motor armature 12 through the contactor 24a and the lead wire 18. The energization of relay coil 34 bythe shifting of contactor 116 therefore places the motor in condition for driving the vehicle in a forward direction.

It is seen that the diode 182 is connected The energization of therelaycoil 128-closes the kcontactor 128a..an dthe energization of the relay coil 136 through diode 130 causesthenclosure. of the contactor 136e.

Since at thistirne therelay coil .198 is not energized, thecontactor .198e will bein a closed position so that the relay coil 74. isenergized viaa circuit that may be traced from i junction. 10.4.through the. contactor @Se through relay coil= .74, through lead ,wire 142 and lthrough the assumed closed contactor 148 to ground. With relay coil 74, energized, itis Vapparentthat thev magnetic switch 72 will'be shifted so that the batteries titl and 68 are connected in `parallel tovk providelZ volts. between .junction vSv and ground.;

If the. operator ofthe. vehiclenow depresses the accelerator d-,a sufficient distance `to close the switch 15?, it-.can ,be seenthatthe relay` coil 52 will be energized from the lead wireSoviacontactor la, switch 15G, lead wire 164,: relay` coil V52, lead Awire 66,` and thence to the junction 62.v Withirelaycoil 52 energized, the contactor SZaiSshifted to. aclosed position, so that l2 volts will now be, appliedbetween the lead wire 50 zand ground. This 12 volts is, of course, appliedI to, the motor 1G through the resistor 4,6.since the. contacter 48a, isnow in an open position.` The motorwill now accelerate with avoltage thatiisequaltoA 112 voltslessthe voltage drop acrossresistordpandzas the motorspeed increases, they time will come whenthe speedhas. reached a sufficient value to cause the centrifugal:switchcontactor 166Yto shift to a closed position.. When contactorl 166 shifts. to a closed position, itcanrbe `seen that the relay coil 4S willbe` energized from the.v lead'wire 162 through the engaged contactsZtlG-g and 196g, With relayA coil 4% energized, the contacter 48a is shifted to a closed `position, so that the powerresistor46;is.now short circuited and a full l2 volts is now applied tothe motorl 1t). This will increase the speedof the motor to a value determined by the l2 volt energizationandthe attainedspeedwill be sufiicient to causeithe centrifugal switchcontactor 174m be shifted to,a,closed position. The operator ofthe vehicle may nowV operate indefinitely at 12 volts by simply maintaining the accelerator pedal-operated switch 15d in a closed position and the Vehicle will-operate at some predeterminedsspeed.

' It is pointedout that in .getting to the 12 volt mode of operation, the shift-,froma lower voltage, for example 6 volts-,w12 volts was not. and-couldn@ be made until the lcentrifugal switch Pcontactor 16,6, was shifted -to ya closed position.

Since the centrifugal switch 174.is now in aclosed Position-.due to the previous 12 volt energization of the motor, itcan be seen thatfwith the closure ofacceleratoroperated switch 152, the. relay coilwinding 1% will be energized; Withrelay coil-winding 196 energized, the Contactlda isshiftedout ofengagernentwith fixed contact 2.00.5 anrlisshiftedinto engagement with the fixed contact 292. It is seen that` this switching, willimmediately deenergize the coil/windingndA to cause the contaeterl 48zto shiftto an open` position and-therefore insert-I the resistor; back in-A the Acircuit-v between the batteries and-,thernotor. A-tgthe same time, the engagement of contact 19nd with fixed-contact 202 will complete a circuit forthe relayv coil Winding, 193 to cause the contactor 19.351 to shift to an openposition. When contactor 198e shifts to an open position, itisseen that` the relay coil 74 will bedenergi'zedandfthe contactors 78 and S0 will thereforebe shifted out ofY engagement with their respective fixed contacts while the contactor- 82 willbe shifted into engagement with4 fixed contacts 92 and 94. This will canse the batteriesttv and 6@ to be connected'in series to provide 24 volts between the junction 58 and ground.

Approximately' 6 volts will'be dropped in theresistor 46 so that the motor now willaccelerate with 18 volts thereto.-

As the motor accelerates with 18 volts applied thereto,

applied the time will corne4 when thel speedof the motor will be sufficient to cause contactor 178 tomove to a closed position. When contacter 178` moves to a closed position, it can be seen that the relay coil 184 will be energized. With relay` coil 184 energized, theI contactor184a is shifted into engagement with a fixed contact 13.6 When the contacts 1S4a and186 are shifted Ainto engagement with each other, it can be seen that the coil` winding 48 will be energized. With coil winding `418 energized, the contacter 48a is shifted to a closed position to oncemore short circuit the voltageA dropping resistortti and therefore cause a full 24 volts to be applied to the motor 10. The. motor may now be.. operated indefinitely atthe 24 volt mode of energization as long as the/accelerator pedal is `depressed sutlicientlyto maintain the switches148,150,y and 152 in a closed position.

It is noted that in going from the 12 volt mode of energization to the 24 volt mode of energization, the motor is accelerated by first applying approximately` l8volts.there to and then applying 24 volts thereto. The shift from 18 volts to 24 volts can only occur after the centrifugal switch 178,:moves toa closed positionand there therefore isprovided a smooth accelerationffor the motor and no sudden current drain on the batteries,

The accelerator operated switch 154 is adapted to provide for rapid acceleration ofthe motor 10A'in the case of emergencies. Ifthe accelerator pedal 1561 is depressed to the point where the` switchlSt-,isclosed it can be seen that the relay coil 134, will be immediatelyf'energized. With relay coil 1&4 energized, the contacts-184r1 and 18,6, become engaged to providel an energizationpathfor the relay coil 43 via diodeslSZ and 1,90 v,and the lead wire 16d; T he energization `of relay coil 4& causes the closure of contact 48a to bypass the power resistor 4o. At the same time that relay coil 184 is energized, the relay coil 1% will beenergized to cause contacts 196;:v and 262 to become engaged. This causes an immediate energization of Vrelay coil .19810 cause the contacter 198e; to be shifted to an open positionand therefore, deenergizerelay coil 74. With relay coil 74 deenergized, thebatteries are immediately connected in series combination to the motor 1d to. apply a full24 Volts thereto around the power resistor 46. It thus is seen that any time the acceleratoroperated switch 154 is. closed, an immediate 24,.volts is applied to the motor for causing an emergency rapidacceleration of the same.

lf the selector switch 112 is shifted such that the movable contactor. 11) engages the reverse contact 116, the vehicle will move inareverse direction since thecurrent through the field 14 of the motor will be reversed. When contacter itlengages the fixed contact 116, it is seen thtthe. relay coil 24will be energized via lead wire 120,v diode 146 and throughthe switch 148.to ground. It is now impossible to energize relay coil 34 since the contactor 11@ has been shifted oftthecontact 114. With relay coil lenergized, the contactor 24a, is shifted out of engagement with contacts 26 and. 28. and the contactor 24h is shifted into engagement with fixed contacts 30 and 32. The. circuit for energizing the motor. is. now lead wire 44, through contactorl 24b, through the field winding 14, through lead wire 22, through contactor 34a, through lead wire l andthence throughthe motor armature to ground. It is seen that the current flow vhas been reversed through the fieldof. the motor to cause a reverse rotation of the motor. With the current ow reversed through the field winding 14 of the motor, the motor will operate in a reverse direction.

Itis importantto note. that in .the reverse position where the contactor engages thefixedcontact 116, it is impossible to energize eitherV relay coil 3,4;or relay coil 128. The diode 13d prevents such energization whereas the diode 122 will permit the,energization of. relay coil 136; Since relay coil 128cannot be energized, contactor 128a remains in an open positionr while the contactorV 136a moves to a closed position.' When contactor136a moves to a closed position, it is possible to move the accelerator 156 to a position wherein switch 150 is closed and therefore applies 6 Volts to the motor. After the motor speed closes centrifugal switch contactor 166, the motor will be energized with 12 volts while moving the vehicle in a reverse direction. Since switch 128e cannot be closed, the motor will never be accelerated in a reverse direction with more than 12 volts applied thereto. This is true since the relay coil 198 cannot be energized due to the open contact 128a and therefore the contactor 198e cannot be opened to cause the series connection of batteries 60 and 68.

The control system for the motor 10 is provided with means for preventing the motor from being reversed in its direction of rotation when the motor is moving the vehicle in one direction at a certain speed. As an example of this, assume that the contactor 110 is in engagement with fixed contact 114 to provide for forward movement of the vehicle. It is seen that the initial energization of the relay coil 106 will be through the centrifugal switch contactor 146. This, of course, causes contactor 106a to close and therefore apply voltage to the shiftable contactor 110. As the speed of the vehicle increases, the centrifugal switch 146 will open, but this will not cause a deenergization of relay coil 106. The relay coil will be energized via a circuit that includes lead wire 126, diode 130, diode 134, and lead wire 144. It thus is seen that the initial opening of the centrifugal switch contactor 146 will not effect operation of the control circuit as long as the vehicle is moving in a forward direction and the vehicle may be accelerated to a speed that results from a full 24 volts energization. If the operator of the vehicle should for some reason now suddenly shift the contactor 110 from the fixed contact 114 to the fixed contact 116, the direction of rotation of the motor 10 will not beimmediately reversed so as to cause damage to the motor and to the parts connecting the motor and the wheels and 16. When the fixed contactor 110 leaves the fixed contact 114, the holding circuit for the relay coil 106 is immediately broken so that the contactor 106a now moves to an open position. The relay coil 106 cannot now be energized through the centrifugal switch contactor 146 since the vehicle is traveling ata speed that has caused this contactor 146 to open. With contactor 106a in an open position, there can be no voltage applied to the relay coil 24 to cause the contactors 24a and 24b to shift, and since the relay coil 34 is deenergized when contact 110 leaves contact 114, there is no voltage at all applied to the motor 12 and it will coast to a stop.

If it is assumed that the vehicle was first started out in a reverse direction by shifting the contactor 110 into en- Y gagernent with the fixed Contact 116, the relay coil 106 will be energized through the centrifugal switch contactor 146 to cause a closure of contact 106a. lf the motor is now accelerated in a reverse direction to provide reverse movement of the vehicle, the centrifugal switch contactor 146 will open at some predetermined speed. The relay coil 106 nevertheless remains energized via a circuit that may be traced from junction 104, through contactor 10661, through switch contactor 110, through lead wire 11S, through lead wire 120, through diodes 12.2 and 134, and thence through lead wire 144, to the relay coil 106. 1f the contactor 110'isnow shifted to the forward contact 114 as the vehicle is moving in a reverse direction, the relay coil 106 is once more immediately deenergized as soon as tl contactor 110 leaves the fixed contact 116. IThis opens the contactor 106a so that when the contactor 110 reaches the contact 114, it cannot attempt to energize the motor for forward rotation.

It can be seen from the foregoing that the system of this invention prevents suddenly attempting to reverse direction of rotation of the drive motore10 when the drive motor is operating in one direction and is moving the vehicle in a predetermined direction.

While .theembodiments ofthe present invention as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A motor control system for an electric motor driven vehicle comprising, an electric motor, a plurality of storage batteries, a power resistor, first switch means normally connecting said batteries in series and operable when shifted to connect said batteries in parallel, a first coil winding for controlling the Yoperation of said first switch means, said first coil winding operating said switch means to shift said batteries to a parallel connection when energized, second switch means connected across said power resistor, a second coil winding for closing said second switch means when energized to thereby short circuit said resistor, means connecting said resistor between said batteries and said motor, a first manually operable switch,

means for causing said first coil winding to be energized when said first manually operable switch is closed, means for causing said second coil winding to be energized in response to the motor attaining a predetermined speed to thereby short circuit said power resistor, a second manually operable switch, means for causing said first coil winding to be deenergized torconnect said batteries in series and for causing said second coil winding torbe deenergized to open the short circuit around said power resistor when said second manually operable switch is closed, means responsive to the speed of said motor for causing said second coil Winding to be energized to short circuit said resistor when said motor attains a second higher speed, and third manually operable switch means for controlling the connection of said motor with said batteries to control its direction of rotation.

2. In a motor control system for'an electric:V motor driven vehicle comprising, an electric motor having an armature and a field winding, a source of voltage, first magnetic switch means including switch contacts and a first coil winding, second magnetic switch means including second switch contacts and a second coil winding, circuit means connecting said voltage source with said motor through said first and second magnetic switch means, said first and second magnetic switch means controlling the direction of current flow through the field winding of said motor to controlV its direction of rotation, an energizing circuit for said first and second coil windings including a two-position switch having a shiftable contactor and fixed contacts connected respectively with said first and second coil windings, third switch means connected between said voltage source and said shiftable contactor, said third switch means being pulled to a closed position by a third coil winding, a first holding circuit for said third coil winding including said shiftable contactor, a second holding circuit for said third coil winding including said shiftable contactor, and centrifugal switch means controlling the connection of said third coil winding with said voltage source, saidcentrifugal switch means being driven by said motor and opening at a predetermined motor speed. f

3. A motor control system for an electric motor driven vehicle comprising, an electric motor, a source of voltage, means for controlling the connection of said motor with said voltage source to control its direction ofV rotation, said last named means being controlled by first and second coil windings, a two-position manually operable switch including a shiftable contactor and fixed contacts connected respectively with said first and second coil windings, third switch means connected between said voltage source and said shiftable contactor and controlled by a third coil winding, a first holding circuit for said third coil winding including said shiftable contactor, a second holding circuit for said third coil winding including said shiftable contactor, and centrifugal switch means operated Y 9 vehicle comprising, rst and second batteries, an electric motor, a resistor, a first electromagnetic switch including a rst coil winding and rst contacts, said first contacts being connected across said resistor and .being closed only when said rst coil winding is energized, a second electromagnetic switch including second contacts and a second coil winding, said second contacts connecting said batteries in parallel when said second coil Winding is energized and operative to connect said batteries in series when said second coil winding is deenergized, rst and second manually operable switch means operated by a common manually operable actuator and closable in a predetermined sequence, rst and second centrifugal switch means driven by said electric motor and closable at different predetermined speeds, a third electromagnetic switch including a third coil winding and third contacts, said third contacts connecting said batteries with said motor through said resistor or through said rst contacts depending upon whether said rst contacts are opened or closed, a control circuit for said third coil winding including said irst manually operable switch means, a control circuit for controlling the energization of said second coil winding including said second manually operable switch means and said second centrifugal switch means, and a control circuit for controlling the energization of said rst coil winding including said first manually operable switch and said rst centrifugal switch means.

References Cited by the Examiner UNITED STATES PATENTS 1,110,821 9/14 Radley 318-139 2,246,803 6/41 Lee 318-325 X 3,134,063 5/64 Hastings 318-139 FOREIGN PATENTS 641,746 8/50 Great Britain.

ORIS L. RADER, Primary Examiner.

20 MILTON O. HIRSHFIELD, Examiner. 

4. A MOTOR CONTROL SYSTEM FOR AN ELECTRIC MOTOR DRIVEN VEHICLE COMPRISING, FIRST AND SECOND BATTERIES, AN ELECTRIC MOTOR, A RESISTOR, A FIRST ELECTROMAGNETIC SWITCH INCLUDING A FIRST COIL WINDING AND FIRST CONTACTS, SAID FIRST CONTACTS BEING CONNECTED ACROSS SAID RESISTOR AND BEING CLOSED ONLY WHEN SAID FIRST COIL WINDING IS ENERGIZED, A SECOND ELECTROMAGNETIC SWITCH INCLUDING SECOND CONTACTS AND A SECOND COIL WINDING, SAID SECOND CONTACTS CONNECTING SAID BATTERIES IN PARALLEL WHEN SAID SECOND COIL WINDING IS ENERGIZED AND OPERATIVE TO CONNECT SAID BATTERIES IN SERIES WHEN SAID SECOND COIL WINDING IS DEENERGIZED, FIRST AND SECOND MANUALLY OPERABLE SWITCH MEANS OPERATED BY A COMMON MANUALLY OPERABLE ACTUATOR AND CLOSABLE IN A PREDETERMINED SEQUENCE, FIRST AND SECOND CENTRIFUGAL SWITCH MEANS DRIVEN BY SAID ELECTRIC MOTOR AND CLOSABLE AT DIFFERENT PREDETERMINED SPEEDS, A THIRD ELECTROMAGNETIC SWITCH INCLUDING A THIRD COIL WINDING AND THIRD CONTACTS, SAID THIRD CONTACTS CONNECTING SAID BATTERIES WITH SAID MOTOR THROUGH SAID RESISTOR OR THROUGH SAID FIRST CONTACTS DEPENDING UPON WHETHER SAID FIRST CONTACTS ARE OPENED OR CLOSED, A CONTROL CIRCUIT FOR SAID THIRD COIL WINDING INCLUDING SAID FIRST MANUALLY OPERABLE SWITCH MEANS, A CONTROL CIRCUIT FOR CONTROLLING THE ENERGIZATION OF SAID SECOND COIL WINDING INCLUDING SAID SECOND MANUALLY OPERABLE SWITCH MEANS AND SAID SECOND CENTRIFUGAL SWITCH MEANS, AND A CONTROL CIRCUIT FOR CONTROLLING THE ENERGIZATION OF SAID FIRST COIL WINDING INCLUDING SAID FIRST MANUALLY OPERABLE SWITCH AND SAID FIRST CENTRIFUGAL SWITCH MEANS. 